The same is usually true of gear tiers, though (And we know they like to keep a lid on crafting early in expansion cycles - the T10 mats still aren't on the Jawa vendors.) Note that I'm not suggesting that this will actually happen, just that people thinking it might could easily cause them to dump their current stash of exotics.

I'd add a a fourth possibility: people speculating (either pure WAG or based on leaked information) that 5.2, along with a new tier of dropped gear, will include a new tier of crafted gear that will require a new exotic to craft, renderiing VMCs (semi)-obsolete.

You'd probably end up spending a lot more money on slicing mats than on blue Investigation mats (check the GTN), since there's more competition - only Armstech uses Investigation mats, but everybody uses Slicing mats. In the long run your best bet is probably "roll up an alt with both Investigation and Slicing" (and maybe Scavenging for a third, to keep you in raw materials and vendor mats). Even if you're out of character slots, check GTN prices for slot unlocks (if you're a sub, they're probably priced out of your escrow limit if you're not, but you might get lucky and hit the "somebody forgot a zero or two" jackpot.)

Crafting used to be the fastest and easiest way to get orange shells back at launch (with a few exceptions - at launch there were zero craftable orange belt/bracer schematics, so finding those pieces was down to lucky drop or spending a fortune on the GTN), and there used to be a bunch of trainer-taught orange shell schematics (they were mostly added later - originally mission skill drops were the main source of schematics) but things changed over time. A lot (but not all) of the old orange schematics are still available as mission drops, although I suspect that's a bug, since they go into the "Archived" section of your schematic list when learned.

There are still at least a couple of orange schematics for each weapon type still available (a bunch got removed during the crafting revamp). They're not on the trainer, you can get the schematics as drops from lower-level Investigation missions (or just check the GTN for Armstech schematics.)

2/4/6 it is I find the 6 schematics actually worth listing on the GTN (they sell slowly but reasonably high; your server's economy may vary), the 4s can be hit-or-miss, and the 2s usually go straight to the vendor.

Investigation also drops Armormech, Synthweaving, Armstech, and Artifice schematics for non-moddable blue gear (which I don't think can be REed for a purple schematic anymore, since they're all archived schematics). It used to drop blue implant/earpiece schematics too, but I haven't see any since the 4.0 changes. The Artifice (and blue Armstech) schematics are basically junk, but some of the skins on the blue armours aren't bad. Slicing also drops Cybertech schematics at lower tiers, for rail-shooter ship parts and mounts.

The Exotic Isotopes can now be purchased from the prototype/blue Jawa scrap vendor. The easiest way to get the Prototype (tier 2, level 70) ones for a solo player is to run the intro flashpoints - Black Talon or Esseles - on Veteran difficulty (ex-normal mode - the option between "Story/solo" and "Hard"), which is quite doable solo.

Another reason so many sets are missing bracer (and belt) schematics is that craftable orange belts and bracers were a later addition to the game - at launch there were zero craftable orange pieces for those slots, in any set (I think they were introduced around 2.0, but I'm not positive), and the only way to get moddabel belt/bracer shells was from drops (they later added some to the space-rail-battles vendor). Back at launch I used to make bank farming some of the Champions near the Dark Temple on DK and the Jedi Temple on Coruscant for belt and bracer shells, which could go for upwards of 500k (back when 500k was a lot of credits.)

The old low-stat crystals are gone, all craftable crystals are now +41 stat (and require purple mats to craft). As you level Artificing you'll learn new colours instead of getting the basic blue/green/red but with better stats every tier. Crystal fragments are also used to craft dyes, and used in some Prefab and Conquest crafting items.

So don't bother buying schematics you don't need? (Your old ones should - mostly - still be available in a section of your schematics list called "Archived".)

You can also get scrap from the weekly Conquest events (you don't have to reach top-10 on the leaderboard, or even be in a guild to get some), as rare-ish drops from the slot machine, and as drops from Galactic Command crates. I'm sure the grade 10 mats will become available for scrap eventually, but in the past it's taken a month or two for them to appear on the vendors for reasons already explained in this thread.

Mission - I haven't done any node-gathering since 5.0 dropped.

Now you have

I haven't done any node-gathering (been focused on running the new story content, haven't bothered doing laps around the Swamps/Breaktown/Darvannis). They're definitely rarer drops than they used to be, but the ones I've gotten have all come from parts missions, directly or indirectly (I got a couple from a Slicing discovery mission.)